As the war in Iraq grinds into its fourth year, a growing proportion of Americans are expressing unfavorable views of Islam, and a majority now say that Muslims are disproportionately prone to violence, according to a new Washington Post-ABC News poll.

The poll found that nearly half of Americans -- 46 percent -- have a negative view of Islam, seven percentage points higher than in the tense months after the Sept. 11, 2001, attacks on the World Trade Center and the Pentagon, when Muslims were often targeted for violence.

The survey comes at a time of increasing tension; the wars in Afghanistan and Iraq show little sign of ending, and members of Congress are seeking to block the Bush administration's attempt to hire an Arab company to manage operations at six of the nation's ports. Also, Americans are reading news of deadly protests by Muslims over Danish cartoons depicting the prophet Muhammad.

Conservative and liberal experts said Americans' attitudes about Islam are fueled in part by political statements and media reports that focus almost solely on the actions of Muslim extremists.

According to the poll, the proportion of Americans who believe that Islam helps to stoke violence against non-Muslims has more than doubled since the attacks, from 14 percent in January 2002 to 33 percent today.

The survey also found that one in three Americans have heard prejudiced comments about Muslims lately. In a separate question, slightly more (43 percent) reported having heard negative remarks about Arabs. One in four Americans admitted to harboring prejudice toward Muslims, the same proportion that expressed some personal bias against Arabs.

Though the two groups are often linked in popular discourse, most of the world's Muslims are not of Arab descent. For example, the country with the largest Muslim population is Indonesia.

As a school bus driver in Chicago, Gary McCord, 65, dealt with many children of Arab descent. "Some of the best families I've ever had were some of my Muslim families," he said in a follow-up interview. "They were so nice to me." He now works for a Palestinian Christian family, whose members he says are "really marvelous."

But his good feelings do not extend to Islam. "I don't mean to sound harsh or anything, but I don't like what the Muslim people believe in, according to the Koran. Because I think they preach hate," he said.

As for the controversial cartoons of Muhammad, he said Arabs seem hypersensitive about religion. "I think it's been blown out of proportion," he said.

Frederick Cole, a welder in Roosevelt, Utah, acknowledged: "As far as being prejudiced against them, I'd have to say maybe a little bit. If I were to go through an airport and I saw one out of the corner of my eye, I'd say, 'I wonder what he's thinking.' " Still, Cole, 30, said, "I don't think the religion is based on just wanting to terrorize people."

A total of 1,000 randomly selected Americans were interviewed March 2-5 for this Post-ABC News poll. The margin of sampling error for the overall results is plus or minus three percentage points.

Americans who said they understood Islam were more likely to see the religion overall as peaceful and respectful. But they were no less likely to say it harbors harmful extremists, and they were also no less likely to have prejudiced feelings against Muslims.

In Gadsden, Ala., Ron Hardy, an auto parts supplier, said Arabs own a lot of stores in his area and "they're okay." But, Hardy, 41, said "I do think" Islam has been "hijacked by some militant-like guys."

Edward Rios, 31, an engineer in McHenry, Ill., said he feels that Islam "is as good a religion as any other" yet vengeance seems to be "built into their own set of beliefs: If someone attacks our people, it is your duty to defend them. . . . I don't think Christianity has anything like that."

James J. Zogby, president of the Washington-based Arab American Institute, said he is not surprised by the poll's results. Politicians, authors and media commentators have demonized the Arab world since 2001, he said.

"The intensity has not abated and remains a vein that's very near the surface, ready to be tapped at any moment," Zogby said. "Members of Congress have been exploiting this over the ports issue. Radio commentators have been talking about it nonstop."

Juan Cole, a professor of modern Middle Eastern and South Asian history at the University of Michigan, agreed, saying Americans "have been given the message to respond this way by the American political elite, mass media and by select special interests."

Cole said he was shocked when a radio talk show host asked him if Islamic extremists would set off a nuclear bomb in the United States in the next six months. "It was ridiculous. I think anti-Arab racism and profiling has become respectable," he said.

Ronald Stockton, a professor of political science at the University of Michigan at Dearborn who helped conduct a study of Arabs in the Detroit area and on views of them held by non-Arabs, said an exceptionally high percentage of non-Muslims feels the media depicts Arabs unfairly, yet still holds negative opinions.

"You're getting a constant drumbeat of negative information about Islam," he said.

Michael Franc, vice president of government relations for the conservative Heritage Foundation, said that the survey responses "seems to me to be a real backlash against Islam" and that congressional leaders do not help the problem by sometimes using language that links all Muslims with extremists.